Toward High Performance Lithium–Sulfur Batteries Based on Li₂S Cathodes and Beyond: Status, Challenges, and Perspectives

Abstract

Lithium sulfur (Li-S) batteries are attracting ever-increasing interests as a new generation rechargeable battery system with high energy density and low cost. Li-S batteries will fulfill their theoretical potential if the problem of polysulfides shuttle effect can be solved. Therefore, tremendous efforts have been devoted to overcoming this problem from the aspects of physical confinement and chemisorption of polysulfides. Recently, it is discovered that replacing sulfur cathodes with lithium sulfide (Li 2 S) can not only largely avoid the volume expansion issue during cycling, but it can also work with anode materials other than lithium metal to eliminate serious safety concerns for traditional Li-S batteries. However, there are many challenges for developing practical Li metal-free Li-S battery systems, because Li 2 S-based cathode materials are moisture-sensitive and prelithiation of the non-Li metal anode materials is usually required for practical applications. This study reviews the recent advances of Li-S batteries based on Li 2 S cathode with features of improved safety, high Coulombic efficiency, and high energy density. The electrode activation processes are also discussed, which is critical for achieving high performances. It is anticipated that the extensive efforts will lead to breakthroughs for the development of Li 2 S cathode -based Li-S batteries.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201800154. the high demand from portable electronic devices, electric vehicles, and smart electricity grids. It has been estimated that the energy storage market will grow from 23 GW h in 2013 to 90.9 GW h in 2020 with a predicted annual growth rate of ≈22%. The lithium (Li)-ion battery is generally considered as a good choice for energy storage and conversion. However, current Li-ion batteries have relatively low energy density due to the low capacity of the electrode materials. [2] In light of the projected orders-of-magnitude increase in Li usage in batteries for low emission hybrid and electric vehicles, [3] concerns have been raised about the limited lithium resources on earth. In order to efficiently utilize the available lithium resources, we must develop advanced lithium batteries with much higher energy density than that of current commercial lithium-ion batteries. [4,5] Among the various alternative energy storage systems, lithium-sulfur (Li-S) batteries, using sulfur as a cathode material, have attracted growing attentions, owing to their high theoretical specific capacity (1675 mAh g −1 ) and specific energy density both in volumetric and gravimetric aspects (2835 Wh L −1 and 2567 Wh kg −1 , respectively). Meanwhile, the low-cost, nontoxic, and environmentally benign cathode active material (elemental sulfur) further makes Li-S batteries become one of the most promising candidates for the next-generation energy storage systems to meet the emerging market requirements.Differing from the intercalation processes in conventional L...

An Atomistic View of the Lithiation/Delithiation Behavior of Carbon Nanotube-Confined Sulfur Cathode for Lithium-Sulfur Batteries

“…1. Moreover, as we observed the inward propagation of lithium getting slower at the later stages, it suggests that the fully lithiated sulfur layer formed in the nanostructure during lithiation could inhibit the ongoing reaction due to the poor electrochemical activity of Li 2 S. [45][46][47][48] Figures 2d and 2h displays the density of the lithiated and delithiated S-NWs having values of between ∼1.63 and 1.9 g cm −3 , corresponding to the densities of bulk amorphous Li 2 S and sulfur, respectively, which are represented with two solid black lines. During Li extraction, the S number density profile changes only slightly from the final lithiation state and it is irreversible (by comparing Figs.…”

Atomically Dispersed and O, N-Coordinated Mn-Based Catalyst for Promoting the Conversion of Polysulfides in Li2S-Based Li–S Battery

“…Moreover, the oxidation peak of Li 2 S/ON-MnPC shows a visible shift to a lower potential, indicating that the atomically dispersed Mn in porous carbon can catalyze the reaction of sulfur oxidation: 8 Li 2 S → 16 Li + S 8 . 43 During the anodic scans, the peaks located at 2.31 and 2.02 V can be attributed to the conversion from S 8 to Li 2 S 4 , and subsequently to Li 2 S 2 or Li 2 S. 44 Apparently, the Li 2 S/ON-MnPC cathode shows a larger peak area and smaller oxidation signal, suggesting that the introduction of Mn atoms can distinctly enhance the conductivity and endow the porous carbon skeleton with catalyzation effect, and thus can harvest a lower polarization and faster conversion reaction kinetics.…”

First-principles study of the discharge electrochemical and catalytic performance of the sulfur cathode host Fe 0.875 M 0.125 S 2 (M = Ti, V)

“…The sulfur cathode host materials not only allow a large number of Li + to be embedded and extracted, but also have a high redox voltage, high electronic conductivity and low Li + diffusion barrier. 30 Monte Carlo with a cluster expansion, based on the first-principles high-throughput calculations, predicts the discharge structure of Fe 0.875 M 0.125 S 2 . Moreover, the redox voltage of FeS 2 is 1.64–2.90 V, and has a high theoretical capacity of 894 mA h g −1 .…”